Abstract

The amorphization process and the thermal properties of amorphous Ti_40Cu_40Ni_10Al_10 powder during milling by mechanical alloying were examined by X-ray diffractometry (XRD), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The chemical composition of the samples was examined by an energy dispersive X-ray spectrometry (EDX) facility attached to the scanning electron microscope (SEM). The as-milled powders showed a broad peak (2theta = 42.4°) with crystalline size of about 5.0 nm in the XRD patterns. The entire milling process could be divided into three different stages: agglomeration (0 < t_m ≤ 3 h), disintegration (3 h < t_m ≤ 20 h), and homogenization (20 h < t_m ≤ 40 h) (t_m: milling time). In the DSC experiment, the peak temperature T_p and crystallization temperature T_x were 466.9°C and 444.3°C, respectively, and the values of T_p, and T_x increased with a heating rate (HR). The activation energies of crystallization for the as-milled powder was 291.5 kJ/mol for T_p.

• Keywords: Mechanical alloying;Amorphous Ti_40Cu_40Ni_10Al_10 powder;Crystalline size;